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        <li class="chapter " data-level="1.1" data-path="../../../">
            
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                    实验简介
            
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        <li class="header">实验之前</li>
        
        
    
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                    环境部署
            
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                    GDB 调试方法*
            
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        <li class="header">实验指导</li>
        
        
    
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                    实验指导零
            
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                    摘要
            
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                    创建项目
            
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                    移除标准库依赖
            
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                    移除运行时环境依赖
            
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                    编译为裸机目标
            
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                    生成内核镜像
            
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                    调整内存布局
            
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                    重写程序入口点
            
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                    使用 QEMU 运行
            
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                    接口封装和代码整理
            
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                    小结
            
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                    实验指导一
            
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        <li class="chapter " data-level="3.2.1" data-path="../../lab-1/guide/intro.html">
            
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                    摘要
            
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        <li class="chapter " data-level="3.2.2" data-path="../../lab-1/guide/part-1.html">
            
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                    什么是中断
            
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        <li class="chapter " data-level="3.2.3" data-path="../../lab-1/guide/part-2.html">
            
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                    RISC-V 中的中断
            
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                    程序运行状态
            
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                    状态的保存与恢复
            
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                    进入中断处理流程
            
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                    时钟中断
            
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                    小结
            
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                    实验指导二
            
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        <li class="chapter " data-level="3.3.1" data-path="../../lab-2/guide/intro.html">
            
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                    摘要
            
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        <li class="chapter " data-level="3.3.2" data-path="../../lab-2/guide/part-1.html">
            
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                    动态内存分配
            
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        <li class="chapter " data-level="3.3.3" data-path="../../lab-2/guide/part-2.html">
            
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                    物理内存探测
            
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                    物理内存管理
            
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                    小结
            
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                    实验指导三
            
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                    摘要
            
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        <li class="chapter " data-level="3.4.2" data-path="../../lab-3/guide/part-1.html">
            
                <a href="../../lab-3/guide/part-1.html">
            
                    
                    从虚拟地址到物理地址
            
                </a>
            

            
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        <li class="chapter " data-level="3.4.3" data-path="../../lab-3/guide/part-2.html">
            
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                    修改内核
            
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                    实现页表
            
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        <li class="chapter " data-level="3.4.5" data-path="../../lab-3/guide/part-4.html">
            
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                    实现内核重映射
            
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                    页面置换*
            
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                    小结
            
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        <li class="chapter " data-level="3.5" >
            
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                    实验指导四
            
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                    摘要
            
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        <li class="chapter " data-level="3.5.2" data-path="../../lab-4/guide/part-1.html">
            
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                    线程和进程
            
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                    线程的创建
            
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                    线程的切换
            
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                    线程的结束
            
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                    内核栈
            
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        <li class="chapter " data-level="3.5.7" data-path="../../lab-4/guide/part-6.html">
            
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                    线程调度
            
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                    小结
            
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                    实验指导五
            
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                    摘要
            
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                    设备树
            
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        <li class="chapter active" data-level="3.6.3" data-path="part-2.html">
            
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                    virtio
            
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        <li class="chapter " data-level="3.6.4" data-path="part-3.html">
            
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                    驱动和块设备驱动
            
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                    文件系统
            
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        <li class="chapter " data-level="3.6.6" data-path="summary.html">
            
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                    小结
            
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                    实验指导六
            
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        <li class="chapter " data-level="3.7.1" data-path="../../lab-6/guide/intro.html">
            
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                    摘要
            
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        <li class="chapter " data-level="3.7.2" data-path="../../lab-6/guide/part-1.html">
            
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                    构建用户程序框架
            
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        <li class="chapter " data-level="3.7.3" data-path="../../lab-6/guide/part-2.html">
            
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                    打包为磁盘镜像
            
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        <li class="chapter " data-level="3.7.4" data-path="../../lab-6/guide/part-3.html">
            
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                    解析 ELF 文件并创建线程
            
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                    实现系统调用
            
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                    处理文件描述符
            
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                    条件变量
            
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                    小结
            
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                    实验一：中断
            
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                    实验二：内存分配
            
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                    实验三：虚实地址转换
            
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                    实验四（上）：线程
            
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                    实验四（下）：线程调度
            
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                    实验六：系统调用
            
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                                <h2 id="virtio">virtio</h2>
<h3 id="&#x6302;&#x8F7D;&#x5230;-qemu">&#x6302;&#x8F7D;&#x5230; QEMU</h3>
<p>&#x4E3A;&#x4E86;&#x8BA9; QEMU &#x6302;&#x8F7D;&#x4E0A;&#x6211;&#x4EEC;&#x865A;&#x62DF;&#x7684;&#x5B58;&#x50A8;&#x8BBE;&#x5907;&#xFF0C;&#x6211;&#x4EEC;&#x8FD9;&#x91CC;&#x9009;&#x4E86; QEMU &#x652F;&#x6301;&#x7684; virtio &#x534F;&#x8BAE;&#xFF0C;&#x9700;&#x8981;&#x5728; QEMU &#x8FD0;&#x884C;&#x7684;&#x65F6;&#x5019;&#x52A0;&#x5165;&#x9009;&#x9879;&#xFF1A;</p>
<p></p><p class="code-label">os/Makefile</p><p></p>
<pre><code class="lang-Makefile"><span class="hljs-comment"># &#x8FD0;&#x884C; QEMU</span>
qemu: build
    @qemu-system-riscv64 \
            -machine virt \
            -nographic \
            -bios default \
            -device loader,file=$(BIN_FILE),addr=0x80200000 \
            -drive file=$(TEST_IMG),format=raw,id=sfs \      <span class="hljs-comment"># &#x6A21;&#x62DF;&#x5B58;&#x50A8;&#x8BBE;&#x5907;</span>
            -device virtio-blk-device,drive=sfs              <span class="hljs-comment"># &#x4EE5; virtio Block Device &#x7684;&#x5F62;&#x5F0F;&#x6302;&#x8F7D;&#x5230; virtio &#x603B;&#x7EBF;&#x4E0A;</span>
</code></pre>
<p>&#x5176;&#x4E2D;&#x7684; <code>TEST_IMG</code> &#x662F;&#x7279;&#x5B9A;&#x6587;&#x4EF6;&#x7CFB;&#x7EDF;&#x683C;&#x5F0F;&#x7684;&#x78C1;&#x76D8;&#x955C;&#x50CF;&#xFF0C;&#x6211;&#x4EEC;&#x5728;&#x672C;&#x5C0F;&#x8282;&#x8FD8;&#x4E0D;&#x4F1A;&#x63D0;&#x53CA;&#x5230;&#x8FD9;&#x4E2A;&#x6982;&#x5FF5;&#xFF0C;&#x8FD9;&#x91CC;&#x53EF;&#x4EE5;&#x76F4;&#x63A5;&#x7528;&#x76EE;&#x5F55;&#x4E0B;&#x7684;&#x6D4B;&#x8BD5;&#x955C;&#x50CF;&#x3002;</p>
<h3 id="&#x4EC0;&#x4E48;&#x662F;-virtio">&#x4EC0;&#x4E48;&#x662F; virtio</h3>
<p>virtio &#x8D77;&#x6E90;&#x4E8E; <a href="https://www.ozlabs.org/~rusty/virtio-spec/virtio-paper.pdf" target="_blank">virtio: Towards a De-Facto Standard For Virtual I/O Devices</a> &#x8FD9;&#x7BC7;&#x8BBA;&#x6587;&#xFF0C;&#x4E3B;&#x8981;&#x9488;&#x5BF9;&#x4E8E;&#x534A;&#x865A;&#x62DF;&#x5316;&#x6280;&#x672F;&#x4E2D;&#x5BF9;&#x901A;&#x7528;&#x8BBE;&#x5907;&#x7684;&#x62BD;&#x8C61;&#x3002;</p>
<blockquote>
<p><strong>[info] &#x5B8C;&#x5168;&#x865A;&#x62DF;&#x5316;&#x548C;&#x534A;&#x865A;&#x62DF;&#x5316;</strong></p>
<p>&#x5728;&#x5B8C;&#x5168;&#x865A;&#x62DF;&#x5316;&#x4E2D;&#xFF0C;&#x88AB;&#x865A;&#x62DF;&#x7684;&#x64CD;&#x4F5C;&#x7CFB;&#x7EDF;&#x8FD0;&#x884C;&#x5728;&#x4F4D;&#x4E8E;&#x7269;&#x7406;&#x673A;&#x5668;&#x4E0A;&#x7684; Hypervisor &#x4E4B;&#x4E0A;&#x3002;&#x88AB;&#x865A;&#x62DF;&#x7684;&#x64CD;&#x4F5C;&#x7CFB;&#x7EDF;&#x5E76;&#x4E0D;&#x77E5;&#x9053;&#x5B83;&#x5DF2;&#x88AB;&#x865A;&#x62DF;&#x5316;&#xFF0C;&#x5E76;&#x4E14;&#x4E0D;&#x9700;&#x8981;&#x4EFB;&#x4F55;&#x66F4;&#x6539;&#x5C31;&#x53EF;&#x4EE5;&#x5728;&#x8BE5;&#x914D;&#x7F6E;&#x4E0B;&#x5DE5;&#x4F5C;&#x3002;&#x76F8;&#x53CD;&#xFF0C;&#x5728;&#x534A;&#x865A;&#x62DF;&#x5316;&#x4E2D;&#xFF0C;&#x88AB;&#x865A;&#x62DF;&#x7684;&#x64CD;&#x4F5C;&#x7CFB;&#x7EDF;&#x4E0D;&#x4EC5;&#x77E5;&#x9053;&#x5B83;&#x8FD0;&#x884C;&#x5728; Hypervisor &#x4E4B;&#x4E0A;&#xFF0C;&#x8FD8;&#x5305;&#x542B;&#x8BA9;&#x88AB;&#x865A;&#x62DF;&#x7684;&#x64CD;&#x4F5C;&#x7CFB;&#x7EDF;&#x66F4;&#x9AD8;&#x6548;&#x5730;&#x8FC7;&#x6E21;&#x5230; Hypervisor &#x7684;&#x4EE3;&#x7801;&#x3002;</p>
<p>&#x5728;&#x5B8C;&#x5168;&#x865A;&#x62DF;&#x5316;&#x6A21;&#x5F0F;&#x4E2D;&#xFF0C;Hypervisor &#x5FC5;&#x987B;&#x6A21;&#x62DF;&#x8BBE;&#x5907;&#x786C;&#x4EF6;&#xFF0C;&#x5B83;&#x662F;&#x5728;&#x4F1A;&#x8BDD;&#x7684;&#x6700;&#x4F4E;&#x7EA7;&#x522B;&#x8FDB;&#x884C;&#x6A21;&#x62DF;&#x7684;&#xFF08;&#x4F8B;&#x5982;&#xFF0C;&#x7F51;&#x7EDC;&#x9A71;&#x52A8;&#x7A0B;&#x5E8F;&#xFF09;&#x3002;&#x5C3D;&#x7BA1;&#x5728;&#x8BE5;&#x62BD;&#x8C61;&#x4E2D;&#x6A21;&#x62DF;&#x5F88;&#x5E72;&#x51C0;&#xFF0C;&#x4F46;&#x5B83;&#x540C;&#x65F6;&#x4E5F;&#x662F;&#x6700;&#x4F4E;&#x6548;&#x3001;&#x6700;&#x590D;&#x6742;&#x7684;&#x3002;&#x5728;&#x534A;&#x865A;&#x62DF;&#x5316;&#x6A21;&#x5F0F;&#x4E2D;&#xFF0C;&#x88AB;&#x865A;&#x62DF;&#x7684;&#x64CD;&#x4F5C;&#x7CFB;&#x7EDF;&#x548C; Hypervisor &#x80FD;&#x591F;&#x5171;&#x540C;&#x5408;&#x4F5C;&#xFF0C;&#x8BA9;&#x6A21;&#x62DF;&#x66F4;&#x52A0;&#x9AD8;&#x6548;&#x3002;&#x534A;&#x865A;&#x62DF;&#x5316;&#x65B9;&#x6CD5;&#x7684;&#x7F3A;&#x70B9;&#x662F;&#x64CD;&#x4F5C;&#x7CFB;&#x7EDF;&#x77E5;&#x9053;&#x5B83;&#x88AB;&#x865A;&#x62DF;&#x5316;&#xFF0C;&#x5E76;&#x4E14;&#x9700;&#x8981;&#x4FEE;&#x6539;&#x624D;&#x80FD;&#x5DE5;&#x4F5C;&#x3002;</p>
</blockquote>
<p>&#x5177;&#x4F53;&#x6765;&#x8BF4;&#xFF0C;virtio &#x7684;&#x67B6;&#x6784;&#x5982;&#x56FE;&#x6240;&#x793A;&#xFF1A;</p>
<div align="center"> <img src="../pics/virtio.gif" style="zoom:100%;"> </div>

<p>&#x4EE5; virtio &#x4E3A;&#x4E2D;&#x5FC3;&#x7684;&#x603B;&#x7EBF;&#x4E0B;&#x53C8;&#x6302;&#x8F7D;&#x4E86; virtio-blk&#xFF08;&#x5757;&#x8BBE;&#x5907;&#xFF09;&#x603B;&#x7EBF;&#x3001;virtio-net&#xFF08;&#x7F51;&#x7EDC;&#x8BBE;&#x5907;&#xFF09;&#x603B;&#x7EBF;&#x3001;virtio-pci&#xFF08;PCI &#x8BBE;&#x5907;&#xFF09;&#x603B;&#x7EBF;&#x7B49;&#xFF0C;&#x672C;&#x8EAB;&#x5C31;&#x6784;&#x6210;&#x4E00;&#x4E2A;&#x8BBE;&#x5907;&#x6811;&#x3002;</p>
<h3 id="virtio-&#x8282;&#x70B9;&#x63A2;&#x6D4B;">virtio &#x8282;&#x70B9;&#x63A2;&#x6D4B;</h3>
<p>&#x5728;&#x4E0A;&#x4E00;&#x8282;&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x5B9E;&#x73B0;&#x4E86;&#x5BF9; &quot;virtio,mmio&quot; &#x7684;&#x8282;&#x70B9;&#x7684;&#x5224;&#x65AD;&#xFF0C;&#x4E0B;&#x9762;&#x6211;&#x4EEC;&#x8FDB;&#x4E00;&#x6B65;&#x6765;&#x533A;&#x5206;&#x4E0A;&#x9762;&#x63D0;&#x5230;&#x7684;&#x90A3;&#x4E9B; virtio &#x8BBE;&#x5907;&#xFF1A;</p>
<p></p><p class="code-label">os/src/drivers/bus/virtio_mmio.rs</p><p></p>
<pre><code class="lang-rust"><span class="hljs-comment">/// &#x4ECE;&#x8BBE;&#x5907;&#x6811;&#x7684;&#x67D0;&#x4E2A;&#x8282;&#x70B9;&#x63A2;&#x6D4B; virtio &#x534F;&#x8BAE;&#x5177;&#x4F53;&#x7C7B;&#x578B;</span>
<span class="hljs-keyword">pub</span> <span class="hljs-function"><span class="hljs-keyword">fn</span> <span class="hljs-title">virtio_probe</span></span>(node: &amp;Node) {
    <span class="hljs-comment">// reg &#x5C5E;&#x6027;&#x4E2D;&#x5305;&#x542B;&#x4E86;&#x63CF;&#x8FF0;&#x8BBE;&#x5907;&#x7684; Header &#x7684;&#x4F4D;&#x7F6E;</span>
    <span class="hljs-keyword">let</span> reg = <span class="hljs-keyword">match</span> node.prop_raw(<span class="hljs-string">&quot;reg&quot;</span>) {
        <span class="hljs-literal">Some</span>(reg) =&gt; reg,
        _ =&gt; <span class="hljs-keyword">return</span>,
    };
    <span class="hljs-keyword">let</span> pa = PhysicalAddress(reg.as_slice().read_be_u64(<span class="hljs-number">0</span>).unwrap() <span class="hljs-keyword">as</span> usize);
    <span class="hljs-keyword">let</span> va = VirtualAddress::from(pa);
    <span class="hljs-keyword">let</span> header = <span class="hljs-keyword">unsafe</span> { &amp;<span class="hljs-keyword">mut</span> *(va.<span class="hljs-number">0</span> <span class="hljs-keyword">as</span> *<span class="hljs-keyword">mut</span> VirtIOHeader) };
    <span class="hljs-comment">// &#x76EE;&#x524D;&#x53EA;&#x652F;&#x6301;&#x67D0;&#x4E2A;&#x7279;&#x5B9A;&#x7248;&#x672C;&#x7684; virtio &#x534F;&#x8BAE;</span>
    <span class="hljs-keyword">if</span> !header.verify() {
        <span class="hljs-keyword">return</span>;
    }
    <span class="hljs-comment">// &#x5224;&#x65AD;&#x8BBE;&#x5907;&#x7C7B;&#x578B;</span>
    <span class="hljs-keyword">match</span> header.device_type() {
        DeviceType::Block =&gt; virtio_blk::add_driver(header),
        device =&gt; <span class="hljs-built_in">println!</span>(<span class="hljs-string">&quot;unrecognized virtio device: {:?}&quot;</span>, device),
    }
}
</code></pre>
<p>&#x4ECE;&#x8BBE;&#x5907;&#x6811;&#x8282;&#x70B9;&#x7684; reg &#x4FE1;&#x606F;&#x4E2D;&#x53EF;&#x4EE5;&#x8BFB;&#x51FA;&#x8BBE;&#x5907;&#x66F4;&#x8BE6;&#x7EC6;&#x4FE1;&#x606F;&#x7684;&#x653E;&#x7F6E;&#x4F4D;&#x7F6E;&#xFF08;&#x5982;&#xFF1A;&#x5728; 0x10000000 - 0x10010000 &#xFF09;&#xFF0C;&#x8FD9;&#x6BB5;&#x533A;&#x95F4;&#x867D;&#x7136;&#x7B97;&#x662F;&#x5185;&#x5B58;&#x533A;&#x95F4;&#xFF0C;&#x4F46;&#x662F;&#x8FD8;&#x8BB0;&#x5F97;&#x7684;&#x5417;&#xFF1F;&#x6211;&#x4EEC;&#x7684;&#x7269;&#x7406;&#x5185;&#x5B58;&#x53EA;&#x5206;&#x5E03;&#x5728; 0x80000000 &#x5230; 0x88000000 &#x7684;&#x7A7A;&#x95F4;&#x4E2D;&#xFF0C;&#x90A3;&#x8FD9;&#x6BB5;&#x7A7A;&#x95F4;&#x54EA;&#x91CC;&#x6765;&#x7684;&#x5462;&#xFF1F;&#x8FD9;&#x5C31;&#x662F;&#x6240;&#x8C13;&#x7684;<strong>&#x5185;&#x5B58;&#x6620;&#x5C04;&#x8BFB;&#x5199; MMIO&#xFF08;Memory Mapped I/O&#xFF09;</strong>&#xFF0C;&#x4E5F;&#x5C31;&#x662F;&#x603B;&#x7EBF;&#x628A;&#x5BF9;&#x8BBE;&#x5907;&#x64CD;&#x4F5C;&#x4FE1;&#x606F;&#x4F20;&#x9012;&#x4E5F;&#x6620;&#x5C04;&#x6210;&#x4E86;&#x5185;&#x5B58;&#x7684;&#x4E00;&#x90E8;&#x5206;&#xFF0C;CPU &#x64CD;&#x4F5C;&#x8BBE;&#x5907;&#x548C;&#x8BBF;&#x95EE;&#x5185;&#x5B58;&#x7684;&#x5F62;&#x5F0F;&#x6CA1;&#x6709;&#x4EFB;&#x4F55;&#x7684;&#x533A;&#x522B;&#xFF0C;&#x4F46;&#x8BFB;&#x5199;&#x6548;&#x679C;&#x662F;&#x4E0D;&#x540C;&#x7684;&#x3002;&#x5927;&#x5BB6;&#x53EF;&#x4EE5;&#x56DE;&#x5FC6;&#x4E00;&#x4E0B;&#x8BA1;&#x7B97;&#x673A;&#x7EC4;&#x6210;&#x539F;&#x7406;&#x4E2D;&#x5BF9;&#x4E32;&#x53E3;&#x7684;&#x8BBF;&#x95EE;&#xFF0C;&#x8FD9;&#x91CC;&#x662F;&#x4E00;&#x4E2A;&#x9053;&#x7406;&#x3002;</p>
<p>&#x6240;&#x4EE5;&#xFF0C;&#x4E3A;&#x4E86;&#x8BBF;&#x95EE;&#x8FD9;&#x6BB5;&#x5730;&#x5740;&#xFF0C;&#x6211;&#x4EEC;&#x4E5F;&#x9700;&#x8981;&#x628A;&#x5B83;&#x52A0;&#x5230;&#x9875;&#x8868;&#x91CC;&#x9762;&#xFF0C;&#x5206;&#x522B;&#x5BF9;&#x5E94;&#x5728; <code>os/src/entry.asm</code> &#x4E2D;&#x7684; <code>boot_page_table</code> &#x4EE5;&#x53CA; <code>os/src/memory/mapping/memory_set.rs</code> &#x7684;&#x65B0;&#x5EFA;&#x5185;&#x6838;&#x7EBF;&#x7A0B;&#x4E2D;&#x52A0;&#x5165;&#x4E86;&#x8FD9;&#x6BB5;&#x5730;&#x5740;&#xFF0C;&#x4F7F;&#x5F97;&#x6211;&#x4EEC;&#x7684;&#x5185;&#x6838;&#x7EBF;&#x7A0B;&#x53EF;&#x4EE5;&#x8BBF;&#x95EE;&#x4ED6;&#x4EEC;&#x3002;</p>
<h3 id="virtiodrivers-&#x5E93;">virtio_drivers &#x5E93;</h3>
<p>&#x6211;&#x4EEC;&#x5728;&#x8FD9;&#x91CC;&#x4E0D;&#x4F1A;&#x81EA;&#x5DF1;&#x6765;&#x5B9E;&#x73B0;&#x9A71;&#x52A8;&#x7684;&#x6BCF;&#x4E00;&#x4E2A;&#x7EC6;&#x8282;&#xFF0C;&#x540C;&#x6837;&#x7684;&#xFF0C;&#x6211;&#x4EEC;&#x4F7F;&#x7528; rCore &#x4E2D;&#x7684; virtio_drivers &#x5E93;&#xFF0C;&#x8FD9;&#x4E2A;&#x5E93;&#x4F1A;&#x5E2E;&#x6211;&#x4EEC;&#x901A;&#x8FC7; MMIO &#x7684;&#x65B9;&#x5F0F;&#x5BF9;&#x8BBE;&#x5907;&#x8FDB;&#x884C;&#x4EA4;&#x4E92;&#xFF0C;&#x540C;&#x65F6;&#x6211;&#x4EEC;&#x4E5F;&#x9700;&#x8981;&#x7ED9;&#x8FD9;&#x4E2A;&#x5E93;&#x63D0;&#x4F9B;&#x4E00;&#x4E9B;&#x8BF8;&#x5982;&#x7533;&#x8BF7;&#x7269;&#x7406;&#x5185;&#x5B58;&#x3001;&#x7269;&#x7406;&#x5730;&#x5740;&#x865A;&#x62DF;&#x8F6C;&#x6362;&#x7B49;&#x63A5;&#x53E3;&#x3002;</p>
<p></p><p class="code-label">os/src/drivers/bus/virtio_mmio.rs</p><p></p>
<pre><code class="lang-rust">lazy_static! {
    <span class="hljs-comment">/// &#x7528;&#x4E8E;&#x653E;&#x7F6E;&#x7ED9;&#x8BBE;&#x5907; DMA &#x6240;&#x7528;&#x7684;&#x7269;&#x7406;&#x9875;&#xFF08;[`FrameTracker`]&#xFF09;</span>
    <span class="hljs-keyword">pub</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">ref</span> TRACKERS: RwLock&lt;BTreeMap&lt;PhysicalAddress, FrameTracker&gt;&gt; =
        RwLock::new(BTreeMap::new());
}

<span class="hljs-comment">/// &#x4E3A; DMA &#x64CD;&#x4F5C;&#x7533;&#x8BF7;&#x8FDE;&#x7EED; pages &#x4E2A;&#x7269;&#x7406;&#x9875;&#xFF08;&#x4E3A; [`virtio_drivers`] &#x5E93;&#x63D0;&#x4F9B;&#xFF09;</span>
<span class="hljs-comment">///</span>
<span class="hljs-comment">/// &#x4E3A;&#x4EC0;&#x4E48;&#x8981;&#x6C42;&#x8FDE;&#x7EED;&#x7684;&#x7269;&#x7406;&#x5185;&#x5B58;&#xFF1F;&#x8BBE;&#x5907;&#x7684; DMA &#x64CD;&#x4F5C;&#x53EA;&#x6D89;&#x53CA;&#x5230;&#x5185;&#x5B58;&#x548C;&#x5BF9;&#x5E94;&#x8BBE;&#x5907;</span>
<span class="hljs-comment">/// &#x8FD9;&#x4E2A;&#x8FC7;&#x7A0B;&#x4E0D;&#x4F1A;&#x6D89;&#x53CA;&#x5230; CPU &#x7684; MMU &#x673A;&#x5236;&#xFF0C;&#x6211;&#x4EEC;&#x53EA;&#x80FD;&#x7ED9;&#x8BBE;&#x5907;&#x4F20;&#x9012;&#x7269;&#x7406;&#x5730;&#x5740;</span>
<span class="hljs-comment">/// &#x800C;&#x9677;&#x4E8E;&#x6211;&#x4EEC;&#x4E4B;&#x524D;&#x6BCF;&#x6B21;&#x53EA;&#x80FD;&#x5206;&#x914D;&#x4E00;&#x4E2A;&#x7269;&#x7406;&#x9875;&#x7684;&#x8BBE;&#x8BA1;&#xFF0C;&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x5047;&#x8BBE;&#x6211;&#x4EEC;&#x8FDE;&#x7EED;&#x5206;&#x914D;&#x7684;&#x5730;&#x5740;&#x662F;&#x8FDE;&#x7EED;&#x7684;</span>
<span class="hljs-meta">#[no_mangle]</span>
<span class="hljs-keyword">extern</span> <span class="hljs-string">&quot;C&quot;</span> <span class="hljs-function"><span class="hljs-keyword">fn</span> <span class="hljs-title">virtio_dma_alloc</span></span>(pages: usize) -&gt; PhysicalAddress {
    <span class="hljs-keyword">let</span> <span class="hljs-keyword">mut</span> pa: PhysicalAddress = <span class="hljs-built_in">Default</span>::default();
    <span class="hljs-keyword">let</span> <span class="hljs-keyword">mut</span> last: PhysicalAddress = <span class="hljs-built_in">Default</span>::default();
    <span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-number">0</span>..pages {
        <span class="hljs-keyword">let</span> tracker: FrameTracker = FRAME_ALLOCATOR.lock().alloc().unwrap();
        <span class="hljs-keyword">if</span> i == <span class="hljs-number">0</span> {
            pa = tracker.address();
        } <span class="hljs-keyword">else</span> {
            <span class="hljs-built_in">assert_eq!</span>(last + PAGE_SIZE, tracker.address());
        }
        last = tracker.address();
        TRACKERS.write().insert(last, tracker);
    }
    <span class="hljs-keyword">return</span> pa;
}

<span class="hljs-comment">/// &#x4E3A; DMA &#x64CD;&#x4F5C;&#x91CA;&#x653E;&#x5BF9;&#x5E94;&#x7684;&#x4E4B;&#x524D;&#x7533;&#x8BF7;&#x7684;&#x8FDE;&#x7EED;&#x7684;&#x7269;&#x7406;&#x9875;&#xFF08;&#x4E3A; [`virtio_drivers`] &#x5E93;&#x63D0;&#x4F9B;&#xFF09;</span>
<span class="hljs-meta">#[no_mangle]</span>
<span class="hljs-keyword">extern</span> <span class="hljs-string">&quot;C&quot;</span> <span class="hljs-function"><span class="hljs-keyword">fn</span> <span class="hljs-title">virtio_dma_dealloc</span></span>(pa: PhysicalAddress, pages: usize) -&gt; <span class="hljs-keyword">i32</span> {
    <span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-number">0</span>..pages {
        TRACKERS.write().remove(&amp;(pa + i * PAGE_SIZE));
    }
    <span class="hljs-number">0</span>
}

<span class="hljs-comment">/// &#x5C06;&#x7269;&#x7406;&#x5730;&#x5740;&#x8F6C;&#x4E3A;&#x865A;&#x62DF;&#x5730;&#x5740;&#xFF08;&#x4E3A; [`virtio_drivers`] &#x5E93;&#x63D0;&#x4F9B;&#xFF09;</span>
<span class="hljs-comment">///</span>
<span class="hljs-comment">/// &#x9700;&#x8981;&#x6CE8;&#x610F;&#xFF0C;&#x6211;&#x4EEC;&#x5728; 0xffffffff80200000 &#x5230; 0xffffffff88000000 &#x662F;&#x90FD;&#x6709;&#x5BF9;&#x5E94;&#x7684;&#x7269;&#x7406;&#x5730;&#x5740;&#x6620;&#x5C04;&#x7684;</span>
<span class="hljs-comment">/// &#x56E0;&#x4E3A;&#x5728;&#x5185;&#x6838;&#x91CD;&#x6620;&#x5C04;&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x6211;&#x4EEC;&#x5DF2;&#x7ECF;&#x628A;&#x5168;&#x90E8;&#x7684;&#x6BB5;&#x653E;&#x8FDB;&#x53BB;&#x4E86;</span>
<span class="hljs-comment">/// &#x6240;&#x4EE5;&#x7269;&#x7406;&#x5730;&#x5740;&#x76F4;&#x63A5;&#x52A0;&#x4E0A; Offset &#x5F97;&#x5230;&#x7684;&#x865A;&#x62DF;&#x5730;&#x5740;&#x662F;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x4EFB;&#x4F55;&#x5185;&#x6838;&#x8FDB;&#x7A0B;&#x7684;&#x9875;&#x8868;&#x6765;&#x8BBF;&#x95EE;&#x7684;</span>
<span class="hljs-meta">#[no_mangle]</span>
<span class="hljs-keyword">extern</span> <span class="hljs-string">&quot;C&quot;</span> <span class="hljs-function"><span class="hljs-keyword">fn</span> <span class="hljs-title">virtio_phys_to_virt</span></span>(pa: PhysicalAddress) -&gt; VirtualAddress {
    VirtualAddress::from(pa)
}

<span class="hljs-comment">/// &#x5C06;&#x865A;&#x62DF;&#x5730;&#x5740;&#x8F6C;&#x4E3A;&#x7269;&#x7406;&#x5730;&#x5740;&#xFF08;&#x4E3A; [`virtio_drivers`] &#x5E93;&#x63D0;&#x4F9B;&#xFF09;</span>
<span class="hljs-comment">///</span>
<span class="hljs-comment">/// &#x9700;&#x8981;&#x6CE8;&#x610F;&#xFF0C;&#x5B9E;&#x73B0;&#x8FD9;&#x4E2A;&#x51FD;&#x6570;&#x7684;&#x76EE;&#x7684;&#x662F;&#x544A;&#x8BC9; DMA &#x5177;&#x4F53;&#x7684;&#x8BF7;&#x6C42;&#xFF0C;&#x8BF7;&#x6C42;&#x5728;&#x5B9E;&#x73B0;&#x4E2D;&#x4F1A;&#x653E;&#x5728;&#x6808;&#x4E0A;&#x9762;</span>
<span class="hljs-comment">/// &#x800C;&#x5728;&#x6211;&#x4EEC;&#x7684;&#x5B9E;&#x73B0;&#x4E2D;&#xFF0C;&#x6808;&#x662F;&#x4EE5; Framed &#x7684;&#x5F62;&#x5F0F;&#x5206;&#x914D;&#x7684;&#xFF0C;&#x5E76;&#x4E0D;&#x662F;&#x9AD8;&#x5730;&#x5740;&#x7684;&#x7EBF;&#x6027;&#x6620;&#x5C04; Linear</span>
<span class="hljs-comment">/// &#x4E3A;&#x4E86;&#x5F97;&#x5230;&#x6B63;&#x786E;&#x7684;&#x7269;&#x7406;&#x5730;&#x5740;&#x5E76;&#x544A;&#x8BC9; DMA &#x8BBE;&#x5907;&#xFF0C;&#x6211;&#x4EEC;&#x53EA;&#x80FD;&#x67E5;&#x9875;&#x8868;</span>
<span class="hljs-meta">#[no_mangle]</span>
<span class="hljs-keyword">extern</span> <span class="hljs-string">&quot;C&quot;</span> <span class="hljs-function"><span class="hljs-keyword">fn</span> <span class="hljs-title">virtio_virt_to_phys</span></span>(va: VirtualAddress) -&gt; PhysicalAddress {
    Mapping::lookup(va).unwrap()
}
</code></pre>
<p>&#x81F3;&#x4E8E;&#x4E3A;&#x4EC0;&#x4E48;&#x8981;&#x5B9E;&#x73B0;&#x8FD9;&#x4E9B;&#x64CD;&#x4F5C;&#xFF0C;&#x662F;&#x56E0;&#x4E3A;&#x672C;&#x8EAB;&#x8BBE;&#x5907;&#x662F;&#x901A;&#x8FC7;<strong>&#x76F4;&#x63A5;&#x5185;&#x5B58;&#x8BBF;&#x95EE;DMA&#xFF08;Direct Memory Access&#xFF09;</strong>&#x6280;&#x672F;&#x6765;&#x5B9E;&#x73B0;&#x6570;&#x636E;&#x4F20;&#x8F93;&#x7684;&#xFF0C;CPU &#x53EA;&#x9700;&#x8981;&#x7ED9;&#x51FA;&#x8981;&#x4F20;&#x8F93;&#x54EA;&#x4E9B;&#x5185;&#x5BB9;&#xFF0C;&#x653E;&#x5728;&#x54EA;&#x6BB5;&#x7269;&#x7406;&#x5185;&#x5B58;&#x4E0A;&#x9762;&#xFF0C;&#x628A;&#x8BF7;&#x6C42;&#x544A;&#x8BC9;&#x8BBE;&#x5907;&#xFF0C;&#x8BBE;&#x5907;&#x540E;&#x9762;&#x7684;&#x64CD;&#x4F5C;&#x5C31;&#x4F1A;&#x5229;&#x7528; DMA &#x800C;&#x4E0D;&#x7ECF;&#x8FC7; CPU &#x76F4;&#x63A5;&#x4F20;&#x8F93;&#xFF0C;&#x5728;&#x4F20;&#x8F93;&#x7ED3;&#x675F;&#x4E4B;&#x540E;&#xFF0C;&#x4F1A;&#x901A;&#x8FC7;<strong>&#x4E2D;&#x65AD;&#x8BF7;&#x6C42; IRQ&#xFF08;Interrupt ReQuest&#xFF09;</strong>&#x6280;&#x672F;&#x6CBF;&#x7740;&#x8BBE;&#x5907;&#x6811;&#x628A;&quot;&#x6211;&#x505A;&#x5B8C;&#x4E86;&quot;&#x8FD9;&#x4E2A;&#x4FE1;&#x606F;&#x544A;&#x8BC9; CPU&#xFF0C;CPU &#x4F1A;&#x4F5C;&#x4E3A;&#x4E00;&#x4E2A;&#x4E2D;&#x65AD;&#x8FDB;&#x4E00;&#x6B65;&#x5904;&#x7406;&#x3002;&#x800C;&#x4E3A;&#x4E86;&#x5B9E;&#x73B0; DMA&#xFF0C;&#x6211;&#x4EEC;&#x9700;&#x8981;&#x4E00;&#x4E9B;&#x8BF7;&#x6C42;&#x548C;&#x5185;&#x5B58;&#x7A7A;&#x95F4;&#xFF0C;&#x6BD4;&#x5982;&#x8BA9;&#x78C1;&#x76D8;&#x628A;&#x6570;&#x636E;&#x4F20;&#x5230;&#x67D0;&#x4E2A;&#x5185;&#x5B58;&#x6BB5;&#xFF0C;&#x6211;&#x4EEC;&#x9700;&#x8981;&#x544A;&#x8BC9;&#x8BBE;&#x5907;&#x5185;&#x5B58;&#x7684;&#x7269;&#x7406;&#x5730;&#x5740;&#xFF08;&#x4E4B;&#x6240;&#x4EE5;&#x4E0D;&#x662F;&#x865A;&#x62DF;&#x5730;&#x5740;&#x662F;&#x56E0;&#x4E3A; DMA &#x4E0D;&#x4F1A;&#x7ECF;&#x8FC7; CPU &#x7684; MMU &#x6280;&#x672F;&#xFF09;&#xFF0C;&#x800C;&#x4E14;&#x8FD9;&#x4E2A;&#x7269;&#x7406;&#x5730;&#x5740;&#x6700;&#x597D;&#x662F;&#x8FDE;&#x7EED;&#x7684;&#x3002;&#x540C;&#x65F6;&#xFF0C;&#x6211;&#x4EEC;&#x5728;&#x6808;&#x4E0A;&#x7533;&#x8BF7;&#x4E00;&#x4E2A;&#x8BF7;&#x6C42;&#x7684;&#x7ED3;&#x6784;&#xFF0C;&#x8FD9;&#x4E2A;&#x7ED3;&#x6784;&#x7684;&#x7269;&#x7406;&#x5730;&#x5740;&#x4E5F;&#x8981;&#x544A;&#x8BC9;&#x8BBE;&#x5907;&#xFF0C;&#x6240;&#x4EE5;&#x4E5F;&#x9700;&#x8981;&#x4E00;&#x4E9B;&#x865A;&#x5B9E;&#x5730;&#x5740;&#x8F6C;&#x6362;&#x7684;&#x63A5;&#x53E3;&#x3002;</p>
<p>&#x73B0;&#x5728;&#xFF0C;&#x6211;&#x4EEC;&#x7684; <code>FRAME_ALLOCATOR</code> &#x8FD8;&#x53EA;&#x80FD;&#x5206;&#x914D;&#x4E00;&#x4E2A;&#x5E27;&#x51FA;&#x6765;&#xFF0C;&#x6211;&#x4EEC;&#x8FDE;&#x7EED;&#x8C03;&#x7528;&#xFF0C;&#x6682;&#x65F6;&#x5148;&#x5047;&#x8BBE;&#x4ED6;&#x662F;&#x8FDE;&#x7EED;&#x7684;&#x3002;&#x540C;&#x65F6;&#x6CE8;&#x610F;&#x5230;&#xFF0C;&#x4E3A;&#x4E86;&#x5B9E;&#x73B0;&#x865A;&#x5B9E;&#x7269;&#x7406;&#x8F6C;&#x6362;&#xFF0C;&#x6211;&#x4EEC;&#x9700;&#x8981;&#x67E5;&#x627E;&#x9875;&#x8868;&#xFF0C;&#x5F88;&#x4E0D;&#x5E78;&#x7684;&#x662F; RISC-V &#x5E76;&#x6CA1;&#x6709;&#x7ED9;&#x6211;&#x63D0;&#x4F9B;&#x4E00;&#x4E2A;&#x5F88;&#x65B9;&#x4FBF;&#x7684;&#x6839;&#x636E;&#x5F53;&#x524D;&#x9875;&#x8868;&#x627E;&#x5230;&#x7269;&#x7406;&#x5730;&#x5740;&#x7684;&#x6307;&#x4EE4;&#xFF0C;&#x6240;&#x4EE5;&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x5728; <code>os/src/memory/mapping/mapping.rs</code> &#x4E2D;&#x5B9E;&#x73B0;&#x4E86;&#x4E00;&#x4E2A;&#x7C7B;&#x4F3C;&#x7684;&#x529F;&#x80FD;&#x3002;</p>
<h3 id="&#x601D;&#x8003;">&#x601D;&#x8003;</h3>
<p>&#x4E3A;&#x4EC0;&#x4E48;&#x7269;&#x7406;&#x5730;&#x5740;&#x5230;&#x865A;&#x62DF;&#x5730;&#x5740;&#x8F6C;&#x6362;&#x76F4;&#x63A5;&#x7EBF;&#x6027;&#x6620;&#x5C04;&#xFF0C;&#x800C;&#x865A;&#x62DF;&#x5730;&#x5740;&#x5230;&#x7269;&#x7406;&#x5730;&#x5740;&#x5374;&#x8981;&#x67E5;&#x8868;&#xFF1F;</p>
<div class="click_reveal"><span> Click to show </span><div><blockquote>
<p>&#x6211;&#x4EEC;&#x62FF;&#x5230;&#x5730;&#x5740;&#x7684;&#x7A76;&#x6781;&#x76EE;&#x7684;&#x662F;&#x8BBF;&#x95EE;&#x5730;&#x5740;&#x4E0A;&#x7684;&#x5185;&#x5BB9;&#xFF0C;&#x9700;&#x8981;&#x6CE8;&#x610F;&#x5230;&#x5728; 0x80000000 &#x5230; 0x88000000 &#x7684;&#x533A;&#x95F4;&#x7684;&#x7269;&#x7406;&#x9875;&#x6709;&#x53EF;&#x80FD;&#x5BF9;&#x5E94;&#x7740;&#x4E24;&#x4E2A;&#x865A;&#x62DF;&#x9875;&#xFF0C;&#x6211;&#x4EEC;&#x5728;&#x542F;&#x52A8;&#x6216;&#x662F;&#x65B0;&#x5EFA;&#x5185;&#x6838;&#x7EBF;&#x7A0B;&#x7684;&#x65F6;&#x5019;&#x90FD;&#x5305;&#x542B;&#x8BF8;&#x5982; 0xffffffff80000000 &#x5230; 0x80000000 &#x8FD9;&#x6837;&#x7684;&#x7EBF;&#x6027;&#x6620;&#x5C04;&#xFF0C;&#x8FD9;&#x610F;&#x5473;&#x7740;&#xFF0C;&#x5728;&#x5185;&#x6838;&#x7EBF;&#x7A0B;&#x91CC;&#x9762;&#xFF0C;&#x53EA;&#x8981;&#x4E00;&#x4E2A;&#x7269;&#x7406;&#x5730;&#x5740;&#x52A0;&#x4E0A;&#x504F;&#x79FB;&#x5F97;&#x5230;&#x7684;&#x865A;&#x62DF;&#x5730;&#x5740;&#x80AF;&#x5B9A;&#x662F;&#x53EF;&#x4EE5;&#x8BBF;&#x95EE;&#x5BF9;&#x5E94;&#x7684;&#x7269;&#x7406;&#x5730;&#x5740;&#x7684;&#x3002;&#x6240;&#x4EE5;&#xFF0C;&#x628A;&#x7269;&#x7406;&#x5730;&#x5740;&#x8F6C;&#x4E3A;&#x865A;&#x62DF;&#x5730;&#x5740;&#x52A0;&#x4E2A;&#x504F;&#x79FB;&#x65E2;&#x53EF;&#x3002;</p>
<p>&#x4E5F;&#x9700;&#x8981;&#x6CE8;&#x610F;&#x5230;&#xFF0C;&#x5185;&#x6838;&#x7EBF;&#x7A0B;&#x867D;&#x7136;&#x4EE3;&#x7801;&#x548C;&#x6570;&#x636E;&#x90FD;&#x662F;&#x7EBF;&#x6027;&#x6620;&#x5C04;&#x7684;&#xFF0C;&#x4F46;&#x662F;&#x5185;&#x6838;&#x6808;&#x662F;&#x4EE5; Frame &#x4E3A;&#x5355;&#x4F4D;&#x5206;&#x914D;&#x7684;&#xFF08;&#x9664;&#x4E86; boot &#x7EBF;&#x7A0B;&#x662F;&#x76F4;&#x63A5;&#x653E;&#x5728; .bss &#x4E2D;&#xFF09;&#xFF0C;&#x800C;&#x4EE5; Frame &#x4E3A;&#x5355;&#x4F4D;&#x5206;&#x914D;&#x610F;&#x5473;&#x7740;&#xFF0C;&#x865A;&#x62DF;&#x5730;&#x5740;&#x53EF;&#x80FD;&#x4ECE; 0 &#x5F00;&#x59CB;&#xFF0C;&#x8FD9;&#x4E2A;&#x65F6;&#x5019;&#x8981;&#x8F6C;&#x4E3A;&#x7269;&#x7406;&#x5730;&#x5740;&#xFF0C;&#x663E;&#x7136;&#x4E0D;&#x662F;&#x51CF;&#x53BB;&#x504F;&#x79FB;&#x91CF;&#x7684;&#x7EBF;&#x6027;&#x6620;&#x5C04;&#xFF0C;&#x800C;&#x5FC5;&#x987B;&#x67E5;&#x5F53;&#x524D;&#x7684;&#x8868;&#x3002;</p>
<p>&#x8FD9;&#x4E2A;&#x65F6;&#x5019;&#xFF0C;&#x4F60;&#x53EF;&#x80FD;&#x95EE;&#x4E86;&#xFF1A;&#x4E3A;&#x4EC0;&#x4E48; RISC-V &#x5904;&#x7406;&#x5668;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x865A;&#x62DF;&#x5730;&#x5740;&#x6765;&#x8BBF;&#x95EE;&#xFF0C;&#x4F46;&#x662F;&#x6211;&#x8FD8;&#x8981;&#x624B;&#x5199;&#x67E5;&#x8868;&#x6765;&#x505A;&#x8FD9;&#x4EF6;&#x4E8B;&#x5462;&#xFF1F;&#x8FD9;&#x662F;&#x56E0;&#x4E3A; RISC-V &#x8FD8;&#x771F;&#x6CA1;&#x6709;&#x76F4;&#x63A5;&#x7528; MMU &#x5F97;&#x5230;&#x5730;&#x5740;&#x7684;&#x6307;&#x4EE4;&#xFF0C;&#x6211;&#x4EEC;&#x53EA;&#x80FD;&#x624B;&#x5199;&#x3002;</p>
</blockquote>
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